how many weeks should i wait!

Hey all! so turns out I'm pregnant!! I just wanted to get some advice because I contacted my doctor and he said to call back in 8 weeks to book an appointment with a midwife. however! I have only just found out and i conceived about two weeks ago but I heard that doctors go from the date of your last period starting so if I calculate it like that then it goes up to 4 weeks and 6 days! so when do I contact the doctor? when do I have to wait for 6 weeks if I've only just conceived or or do I just have to wait 4 weeks? this is so confusing and I haven't really had any guidance so any advice on here would be great